Appropriate Discharge from Diversion Dam to Dilute High Concentrated Community Wastewater of Riverbank Settlements along Phetchaburi River in Phetchaburi Province, Thailand

Abstract

The research was focused on determining dilatability of traveling mass water from Phetchaburi diversion dam on high concentrated community wastewater that flowing into Phetchaburi river. The mass water quality was sampled at six-consecutive measuring stations from Phetchaburi diversion dam to the river mouth with various distances of traveling, and analyzed for 27 environmental indicators before employing ANOVA ANALYSIS which resulted with highly significant differences between indicator and station only BOD, COD, TSS, and turbidity. When the linear regression was employed to determine both the water quality indicators in relation to discharges (10, 15, 20, and 25 cms.) and the traveling distances, resulting the determination coefficients of 0.93 for BOD, 0.80 for COD, 0.83 for TSS, and 0.50 for turbidity. Only BOD value is included in the list of surface water quality standards. After employing the derived equations to calculate BOD in comparison with observed value, then it was chosen to support the decision of required BOD for 3 mg/L at Muang Municipal Bridge together with discharge of 10-15 cms from Phetchaburi diversion dam. If more or less this range in summer period, the dilatability of high contaminant concentration was decreased 2-10 folds due to less mass water flow and washing off organic and solid wastes from flooding along the riverbanks. Furthermore, the traveling mass water from diversion dam is possibly eligible to dilute the high concentrated wastewater from dense and populated community but the diluted mixture depending on the amount and concentration of wastewater inflow.